Utility Network Communications Using Meter Identifiers

ABSTRACT

An electronic electric meter for use in a networked automatic meter reading environment. The meter includes a meter microcontroller, a measurement microcontroller, a communication microcontroller and spread spectrum processor, and a plurality of other communication interface modules for communicating commodity utilization and power quality data to a utility. The meter measures electricity usage and monitors power quality parameters for transmission to the utility over a spread spectrum local area network (LAN) to a remotely located gateway node. The gateway node transmits this data to the utility over a commercially available fixed wide area network (WAN). The meter also provides direct communication to the utility over a commercially available network interface that plugs into the meter&#39;s backplane or bus system, bypassing the local area network communication link and gateway node.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 11/894,333,filed Aug. 21, 2007, which is a divisional of application Ser. No.10/672,781, filed Sep. 26, 2003, now U.S. Pat. No. 7,277,027, which is acontinuation of application Ser. No. 10/319,856, filed Dec. 13, 2002,now abandoned, which is a continuation of application Ser. No.09/242,792, filed Sep. 5, 1997, now U.S. Pat. No. 6,538,577.

BACKGROUND OF THE INVENTION

The present invention relates to apparatus for measuring usage of acommodity. More particularly, the invention relates to an electronicelectric meter for measuring consumption of electricity andcommunicating that usage data and other power information to a utilityover a two-way wireless local area network (LAN) to a remotely locatedgateway node that transmits the data over a two-way fixed common carrierwide area network (WAN), or communicating that data directly to theutility, over a commercially available two-way data communicationnetwork.

Commodity usage is conventionally determined by utility companies usingmeters that monitor subscriber consumption. The utility service providertypically determines the subscriber's consumption by sending a serviceperson to each meter location to manually record the informationdisplayed on the meter dial. The manual reading is then entered into acomputer which processes the information and outputs a billing statementfor the subscriber. However, it is often difficult for the serviceperson to access the meter for reading, inspection and maintenance. Whenaccess to a meter is not possible, billings are made on the basis ofestimated readings. These estimated billings often lead to customercomplaints.

Currently available electric meters such as watt-hour meters work wellfor their intended purpose, but they must be manually read. This makesit difficult to cost effectively measure electricity usage for each userto promote fair billing and encourage conservation. Manual reading ofelectric meter is highly labor intensive, inefficient and veryexpensive. Therefore, there has been a strong interest on the part ofutility companies to take advantage of modern technology to reduceoperating costs and increase efficiency by eliminating the necessity formanual readings.

Many attempts have been made in recent years to develop an automaticmeter reading system for electric meters which avoid the high costs ofmanual meter reading. However, most of these prior art systems haveachieved little success. For automatic or remote meter reading, atransducer unit must be used with the meters to detect the output ofsuch meters and transmit that information back to the utility.

Various types of devices have been attached to utility meters in aneffort to simplify meter reading. These devices were developed totransfer commodity usage data over a communication link to a centrallylocated service center or utility. These communication links includedtelephone lines, power lines, or a radio frequency (RF) link.

The use of existing telephone lines and power lines to communicatecommodity usage data to a utility have encountered significant technicaldifficulties. In a telephone line system, the meter data may interferewith the subscriber's normal phone line operation, and would requirecooperation between the telephone company and the utility company forshared use of the telephone lines. A telephone line communication linkwould also require a hard wire connection between the meter and the maintelephone line, increasing installation costs. The use of a power linecarrier (PLC) communication link over existing power lines would againrequire a hard wire connection between the meter and the main powerline. Another disadvantage of the PLC system is the possibility oflosing data from interference on the power line.

Meters have been developed which can be read remotely. Such meters areconfigured as transducers and include a radio transmitter fortransmitting data to the utility. These prior art systems required themeter to be polled on a regular basis by a data interrogator. The datainterrogator may be mounted to a mobile unit traveling around theneighborhood, incorporated within a portable hand-held unit carried by aservice person, or mounted at a centrally located site. When the meteris interrogated by an RF signal from the data interrogator, the meterresponds by transmitting a signal encoded with the meter reading and anyother information requested. The meter does not initiate thecommunication.

However, such prior art systems have disadvantages. The firstdisadvantage is that the device mounted to the meter generally has asmall transceiver having a very low power output and thus a very shortrange. This would require that the interrogation unit be in closeproximity to the meters. Another disadvantage is that the deviceattached to the meter must be polled on a regular basis by the datainterrogator. The device attached to the meter is not able to initiate acommunication. The mobile and hand-held data interrogators are oflimited value since it is still necessary for utility service personnelto travel around neighborhoods and businesses to remotely read themeters. It only avoids the necessity of entering a residence or otherbuilding to read the meters. The systems utilizing a data interrogatorat fixed locations still have the disadvantages of low power output fromthe devices attached to the meters, and requiring polling by the datainterrogator to initiate communication.

Therefore, although automatic meter reading systems are known in theprior art, the currently available automatic meter reading systemssuffer from several disadvantages, such as low operating range andcommunication reliability. Thus, it would be desirable to provide anelectronic electric meter to retrofit into existing meter sockets or fornew installations that enables cost effective measurement of electricityusage by a consumer. It would also be desirable to have an electricmeter that is capable of providing automatic networked meter reading.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an integrated fullyelectronic electric meter that retrofits into existing meter sockets andis compatible with current utility operations.

Another object of the invention is to provide an electronic electricmeter that communicates commodity utilization data and power qualityinformation to a utility over a two-way wireless spread spectrum localarea network to a gateway node that transmits the data over a two-wayfixed common carrier wide area network, or communicates the datadirectly to the utility over a commercially available two-way datacommunication network.

A further object of the invention is to provide a gateway node forreceiving commodity utilization data and power quality information fromthe electric meter and transmitting that data to a utility serviceprovider over a commercially available fixed common carrier wide areanetwork.

Yet another object of the invention is to provide an electronic electricmeter that communicates commodity utilization data and power qualityinformation upon interrogation by a communication node, at preprogrammedscheduled reading times, and by spontaneous reporting of tamper or poweroutage conditions.

Yet another object of the invention is to provide an electronic electricmeter that is of a modular construction to easily allow an operator tochange circuit boards or modules depending upon the desired datacommunication network.

The present invention is a fully electronic electric meter forcollecting, processing and transmitting commodity utilization and powerquality data to a utility service provider.

The electronic electric meter is of a modular design allowing for theremoval and interchangeability of circuit boards and modules within themeter. All of the circuit boards and modules plug into a commonbackplane or busing system.

The electric meter is able to communicate commodity utilization data andpower quality information to a utility over a local area network (LAN)or a wide area network (WAN). A radio frequency (RF) transceiver locatedwithin the meter creates a LAN link between the meter and a gateway nodelocated remotely from the meter. This LAN utilizes a 900 MHz spreadspectrum communication technique for transmitting commodity utilizationdata and power quality information from the meter to the gateway node,and for receiving interrogation signals from the gateway node.

The electric meter is also able to communicate directly with the utilitythrough the variety of commercially available communication networkinterface modules that plug into the meter's backplane or bus system.For example, these modules might include a narrowband personalcommunication services (PCS) module or a power line carrier (PLC)module. For these modules, a gateway node is not necessary to completethe communication link between the meter and the utility.

The gateway node is located remotely from the meter to complete thelocal area network. The gateway node is also made up of four majorcomponents. These components include a wide area network interfacemodule, an initialization microcontroller, a spread spectrum processorand an RF transceiver. The gateway node is responsible for providinginterrogation signals to the meter and for receiving commodityutilization data from the interface management unit for the local areanetwork. However, the gateway node also provides the link to the utilityservice provider over a commercially available fixed two-way commoncarrier wide area network.

The RF transceiver of the gateway node transmits interrogation signalsfrom the utility or preprogrammed signals for scheduled readings to theelectric meter, and receives commodity utilization data in return fromthe meter for transmission to the utility over the wide area network.The spread spectrum processor is coupled to the RF transceiver andenables the gateway node to transmit and receive data utilizing thespread spectrum communication technique. The WAN interface module iscoupled to the spread spectrum processor and transmits data to and fromthe utility service provider over any commercially available wide areanetwork that is desired. A different WAN interface module can be usedfor each different commercially available wide area network desired. Theinitialization microcontroller is interposed between the interfacemodule and the spread spectrum processor for controlling operation ofthe spread spectrum processor and for controlling communication withinthe gateway node.

Meter reading, meter information management and network communicationsare all controlled by two-way system software that is preprogrammed intothe electric meter's memory during manufacture and installation. Thesoftware enables an operator to program utility identification numbers,meter settings and readings, units of measure and alarm set points.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of an electronic electric meter inaccordance with the present invention;

FIG. 2 is a cross-sectional view of the internal structure of theelectric meter shown in FIG. 1;

FIG. 3 is a block diagram of the electric meter circuitry;

FIG. 4 is a front elevational view of a gateway node;

FIG. 5 is a schematic view of the electric meter interfacing with aremote gateway node and a utility service provider, creating a networkedautomatic meter reading data communication system;

FIG. 6 is a flow diagram of the automatic meter reading datacommunication system shown in FIG. 5;

FIG. 7 is a block diagram of the gateway node circuitry;

FIG. 8 is a functional block diagram of the automatic meter reading datacommunication system of FIGS. 5 and 6;

FIG. 9A is a flow diagram of the WAN handler portion of the datacommunication system of FIG. 8;

FIG. 9B is a flow diagram of the message dispatcher portion of the datacommunication system of FIG. 8;

FIG. 9C is a flow diagram of the RF handler portion of the datacommunication system of FIG. 8;

FIG. 9D is a flow diagram of the scheduler portion of the datacommunication system of FIG. 8; and

FIG. 9E is a flow diagram of the data stores portion of the datacommunication system of FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION Electronic Electric Meter

FIGS. 1 and 2 show a fully integrated, self-contained electronicelectric meter 10 for measuring electricity usage and monitoring powerquality. The meter 10 is operable for both single phase and three phaseelectric power installations. The meter 10 includes a top cover 12attached to a meter base 14. Extending outwardly from the meter base 14is a mounting frame 16 and a pair of terminals 18, 20. The meter 10easily retrofits into existing meter sockets by insertion of terminals18, 20 into the sockets and interlocking the mounting frame to securethe meter in place. The terminals 18, 20 complete the connection betweenthe electric power line and the meter 10. The meter 10 further includesa liquid crystal display 22 for displaying meter readings and settings,units of measure and status conditions. The top cover 12 includes arectangular opening 24 for the LCD 22. A rectangularly shapedtransparent piece of glass or plastic covers the rectangular opening 24for viewing LCD 22.

As shown in FIG. 2, the fully electronic, self-contained, modularelectric meter 10 includes several electronic sub-assemblies. Thesub-assemblies include a power transformer 32, a current transformer 34,a power/meter circuit board 36, an interface management unit circuitboard 38, an RF transceiver sub-assembly 40, an LCD sub-assembly 42, anda variety of commercially available plug in network modules, such as anarrowband personal communication services (PCS) module 41 and a powerline carrier (PLC) module 43.

All of the circuit boards and modules plug into a common backplane orbusing system (not shown) providing a modular construction allowing forinterchangeability of circuit boards and modules depending on the datacommunication network desired. While the meter 10 is shown as anelectric meter, the meter 10 can also be configured to measure otherphysical characteristics such as water and gas.

Circuitry of Electronic Electric Meter

FIG. 3 shows a block diagram of the electric meter's internal circuitry.The meter 10 is powered directly from the electric power line comingthrough terminals 18, 20 and into power transformer 32 to provide the DCpower required of the meter circuitry. Back up battery power 44 isprovided in case of electrical power outages.

The electrical power flowing through terminals 18 and 20 is sensed byvoltage interface transducer 46 and current interface transducer 48. Theaccumulated pulse totalization from transducers 46 and 48 is input intometer microcontroller 50 which interprets the electrical signal datareceived from transducers 46 and 48. The processed electrical signaldata is then sent through a level translator 52 to condition the signalsfor the required input into measurement microcontroller 54. Measurementmicrocontroller 54 performs additional calculations on the electricalsignals received from meter microcontroller 50 and prepares them foroutput to the LCD 22 or an appropriate communication network. Metermicrocontroller 50 may comprise the integrated circuit sold by SAMES ofSouth Africa under the designation SA9603B. The measurementmicrocontroller 54 is an SMOS chip available under the designation SMCAA316F03.

The measurement microcontroller 54 also monitors inputs from tamperswitch 56 and disconnect relay 57 for disconnecting the meter from theelectrical line. The program ROM 59 contains customer specific and sitespecific variables that may be important for calculating electricityusage. The meter 10 has an accuracy of approximately 0.2% for a powerinput current range of 0-200 amps. Other features that the measurementmicrocontroller 54 is able to measure are kilowatt hour usage, voltageand frequency measurements, energy direction, time and date reporting,load profiling and failure reporting. The power/meter circuit boardincludes measurement microcontroller 54, level translator 52, metermicrocontroller 50, backup battery 44, and primary power supply 32.

Electric meter 10 is able to communicate commodity utilization data andpower quality information to a utility over a local area network (LAN)or a wide area network (WAN). A radio frequency (RF) communicationsection within the electric meter 10 is comprised by a communicationmicrocontroller and a spread spectrum processor chip 58 and an RFtransceiver 60. An antenna 62 is coupled to the RF transceiver 60 fortransmitting and receiving RF spread spectrum signals.

The communication microcontroller portion of chip 58 is responsible forall aspects of radio frequency (RF) communication management in electricmeter 10 including determining the presence of a valid interrogatingsignal from a remotely located gateway node. The communicationmicrocontroller portion of chip 58 provides control information tospread spectrum processor portion of chip 58 and RF transceiver 60 tocontrol spread spectrum protocol and RF channelization. Communicationmicrocontroller and spread spectrum processor chip 58 may comprise theintegrated circuit sold by Siliconians of California, under thedesignation SS105.

The spread spectrum communication technique makes use of a sequentialnoise-like signal structure, for example, pseudo-noise (PN) codes tospread a normally narrowband information signal over a relatively wideband of frequencies. This spread spectrum communication technique may befurther understood by reference to U.S. Pat. No. 5,166,952 and thenumerous publications cited therein.

The use of the spread spectrum communication technique, when used inconjunction with the direct sequence modulation technique, hereinafterdescribed, gives the LAN data communication system a measure ofsecurity. This communication technique also avoids the need to obtainlicensure from governmental authorities controlling radio communication.

The spread spectrum processor portion of chip 58 functions to performspread spectrum encoding of the data from communication microcontrollerprovided to RF transceiver 60 and decoding of the spread spectrum datafrom the RF transceiver. A better understanding of the spread spectrumcommunication technique can be obtained by reading the subject matterunder the subheading entitled “Circuitry of Gateway Node”. The RFtransceiver 60 and communication microcontroller and spread spectrumprocessor chip 58 are part of the circuitry on interface management unitboard 38 and RF module 40 of FIG. 2.

The meter 10 also includes plugin interface modules which correspond toa variety of different commercially available LAN or WAN communicationdevices. These communication devices provide a communication linkdirectly from the electric meter 10 to a utility service provider. Forexample, shown in FIG. 3, is a narrow band personal communicationservices (PCS) interface module 64, and a power line carrier (PLC)interface module 66 powered by a PLC interface power supply 68. Thesecommunication interface modules are easily interchangeable withinelectric meter 10. These modules communicate with the measurementmicrocontroller 54 and an interface microcontroller 70 along a commonbackplane or busing system (not shown). Exemplary meter interfacesincludes the PowerPoint electronic meter interface for the GE KVII meterequipped with an internal antenna, or the GE KVII meter equipped withexternal antenna. When the meter 10 is configured to measure water oraqueous characteristics, a water interface management unit (“IMU”)interface such as the Silver Spring Network water IMU can be used. Whenthe meter 10 is configured to measure gaseous characteristics, theSilver Spring Network gas IMU is an exemplary interface. Other exemplaryinterfaces include MTC Raven communications package V2.2, Siemens S4communication package V2.2, or Schlumberger Vectron communicationpackage V2.2.

Networked Automatic Meter Reading Data Communication System

In a preferred embodiment of the invention, FIGS. 5 and 6, the electricmeter 10 communicates over a local area network (LAN) 74 to a gatewaynode 72 which transmits the commodity data from the electric meter 10 toa utility 76 over a fixed common carrier wide area network (WAN) 78. Thegateway node 72 provides the end to end communication links from themeter 10 to the utility 76. A first link in the data communicationsystem is a two-way 900 MHz spread spectrum LAN 74. The second linkwithin the data communication system is designed to be any commerciallyavailable two-way common carrier WAN 78. In this embodiment, a gatewaynode 72 must be within the communication range of the electric meter 10which is approximately one mile.

In an alternate embodiment, the electric meter 10 provides direct localarea and wide area network access through printed circuit boardsub-assemblies installed in meter 10 described above.

A more detailed representation of the preferred embodiment is shown inFIGS. 8 and 9A-9E. FIG. 8 shows a functional flow diagram of thenetworked automatic meter reading data communication system of thepresent invention in which the components are described as functionalblocks. The flow diagram FIG. 8, includes the main functional componentsof the gateway note 72 which include a message dispatcher 80, an RFhandler 82, a WAN handler 84, a data stores component 86 and a schedulercomponent 88. The data stores and scheduler components comprise datathat is preprogrammed into the gateway node's memory. The gateway node72 interfaces with the electric meter 10 over the two-way wireless LAN74. The gateway node 72 also interfaces with the utility serviceprovider 76 over the fixed common carrier WAN 78.

FIG. 9A is a detailed functional diagram of the WAN handler 84 of FIG.8. In a typical communication episode, the utility 76 may initiate arequest for data from the electric meter 10 by sending a data streamover the WAN 78. The WAN handler 84 of the gateway node 72 receives theWAN data stream, creates a WAN message, verifies the utility ID of thesender from the data stores 86 and routes the WAN message to the messagedispatcher 80 in the gateway node.

Referring now to FIG. 9B, the message dispatcher 80 receives the WANmessage from the WAN handler 84 and determines the request from theutility 76. The message dispatcher 80 determines that the end recipientor target is the electronic meter 10. The message dispatcher 80 thenverifies the meter ID from the data stores 86, creates an RF message androutes the RF message to the RF handler 82.

Referring now to FIG. 9C, the RF handler 82 receives the RF message fromthe message dispatcher 80, selects a proper RF channel, converts the RFmessage to an RF data stream, sends the RF data stream to the electricmeter 10 over the LAN 74 and waits for a response. The electric meter 10then responds by sending an RF data stream over the LAN 74 to the RFhandler 82 of the gateway node 72. The RF handler 82 receives the RFdata stream, creates an RF message from the RF data stream and routesthe RF message to the message dispatcher 80. As shown in FIG. 9B, themessage dispatcher 80 receives the RF message, determines the targetutility for response from the data stores 86, creates a WAN message androutes the WAN message to the WAN handler 84. The WAN handler 84receives the WAN message from the message dispatcher 80, converts theWAN message to a WAN data stream and sends the WAN data stream to theutility 76 over the fixed common carrier WAN 78, as shown in FIG. 9A tocomplete the communication episode.

A communication episode can also be initiated by scheduled readingspreprogrammed into the scheduler 88 of the gateway node as shown in FIG.9D. A list of scheduled reading times is preprogrammed into memorywithin the gateway node 72. The scheduler 88 runs periodically when ascheduled reading is due. When it is time for a scheduled reading, thescheduler 88 retrieves meter 10 information from the data stores 86,creates an RF message and routes the RF message to the RF handler 82,receives the RF message, selects a proper RF channel, converts the RFmessage to an RF data stream, sends the RF data stream to the electricmeter 10 and waits for a response. The meter then responds with an RFdata stream to the RF handler 82. The RF handler 82 receives the RF datastream, creates an RF message from the RF data stream and routes the RFmessage to the message dispatcher 82. The message dispatcher 80 receivesthe RF message, determines the target utility for response from the datastores 86, creates a WAN message and routes the WAN message to the WANhandler 84. The WAN handler 84 receives the WAN message, converts theWAN message to a WAN data stream and sends the WAN data stream to theutility 76.

Occasionally, the utility 76 may request data that is stored within thegateway node's memory. In this case, the utility 76 initiates thecommunication episode by sending a WAN data stream to the WAN handler84. The WAN handler 84 receives the WAN data stream, creates a WANmessage, verifies the utility ID of the sender in the data stores 86 androutes the WAN message to the message dispatcher 80. As shown in FIG.15B, the message dispatcher 80 receives the WAN message and determinesthe request from the utility 76. The message dispatcher 80 thendetermines the target of the message. If the data requested is stored inthe gateway node memory, then the gateway node 72 performs the requestedtask, determines that the requesting utility is the target utility for aresponse, creates a WAN message and routes the WAN message to the WANhandler 84. The WAN handler 84 receives the WAN message, converts theWAN message to a WAN data stream and sends the WAN data stream to theutility 76.

The last type of communication episode is one which is initiated by theelectric meter 10. In this case, the meter detects an alarm outage ortamper condition and sends an RF data stream to the RF handler 82 of thegateway node 72. The RF handler 82 receives the RF data stream, createsan RF message from the RF data stream and routes the RF message to themessage dispatcher 80. The message dispatcher 80 receives the RFmessage, determines the target utility for response from the data stores86, creates a WAN message and routes the WAN message to the WAN handler84. The WAN handler 84 receives the WAN message, converts the WANmessage to a WAN data stream and sends the WAN data stream to theutility 76.

There are thus three different types of communication episodes that canbe accomplished within the automatic meter reading data communicationsystem shown in FIGS. 8 and 9A-E. The automatic meter reading functionsincorporated in electric meter 10 include monthly usage readings, demandusage readings, outage detection and reporting, tamper detection andnotification, load profiling, first and final meter readings, andvirtual shutoff capability.

FIG. 9D represents information or data that is preprogrammed into thegateway node's memory. Included within the memory is a list of scheduledreading times to be performed by the interface management unit. Thesereading times may correspond to monthly or weekly usage readings, etc.

FIG. 9E represents data or information stored in the gateway node'smemory dealing with registered utility information and registeredinterface management unit information. This data includes the utilityidentification numbers of registered utilities, interface managementunit identification numbers of registered interface management units,and other information for specific utilities and specific interfacemanagement units, so that the gateway node may communicate directly withthe desired utility or correct electric meter.

Electronic Electric Meter Virtual Shut-Off Function

The virtual shut-off function of the electric meter 10 is used forsituations such as a change of ownership where a utility service is tobe temporarily inactive. When a residence is vacated there should not beany significant consumption of electricity at that location. If there isany meter movement, indicating unauthorized usage, the utility needs tobe notified. The tamper switch 56 of the electric meter 10 provides ameans of flagging and reporting meter movement beyond a preset thresholdvalue.

Activation of the virtual shut-off mode is accomplished through the “setvirtual threshold” message, defined as a meter count which the electricmeter is not to exceed. In order to know where to set the threshold itis necessary to know the present meter count. The gateway node reads themeter count, adds whatever offset is deemed appropriate, sends theresult to the electric meter as a “set virtual shut-off” message. Theelectric meter will then enable the virtual shut-off function. Theelectric meter then accumulates the meter counts. If the meter count isgreater than the preset threshold value then the electric meter sends a“send alarm” message to the gateway node until a “clear error code”message is issued in response by the gateway node. However, if the metercount is less than the preset threshold value then the electric metercontinues to monitor the meter count. The virtual shut-off function maybe canceled at any time by a “clear error code” message from the gatewaynode.

If the meter count in the meter does not exceed the preset thresholdvalue at any given sampling time, then the meter continues to countuntil the preset threshold count is attained or until operation in thevirtual shut-off mode is canceled.

Gateway Node

The gateway node 72 is shown in FIG. 4. The gateway node 72 is typicallylocated on top of a power pole or other elevated location so that it mayact as a communication node between LAN 74 and WAN 78. The gateway node72 includes an antenna 90 for receiving and transmitting data over theRF communication links, and a power line carrier connector 92 forconnecting a power line to power the gateway node 72. The gateway node72 may also be solar powered. The compact design allows for easyplacement on any existing utility pole or similarly situated elevatedlocation. The gateway node 72 provides end to end communications fromthe meter 10 to the utility 76. The wireless gateway node 72 interfaceswith the electric meter 10 over a two-way wireless 900 MHz spreadspectrum LAN 74. Also, the gateway node 72 will interface and becompatible with any commercially available WAN 78 for communicatingcommodity usage and power quality information with the utility. Thegateway node 72 is field programmable to meet a variety of datareporting needs.

The gateway node 72 receives data requests from the utility,interrogates the meter and forwards commodity usage information, as wellas power quality information, over the WAN 78 to the utility 76. Thegateway node 72 exchanges data with certain, predetermined, meters forwhich it is responsible, and “listens” for signals from those meters.The gateway node 72 does not store data for extended periods, thusminimizing security risks. The gateway node's RF communication range istypically one mile.

A wide variety of fixed wide area network (WAN) communication systemssuch as those employed with two-way pagers, cellular telephones,conventional telephones, narrowband personal communication services(PCS); cellular digital packet data (CDPD) systems, and satellites maybe used to communicate data between the gateway nodes and the utility.The data communication system utilizes channelized direct sequence 900MHz spread spectrum transmissions for communicating between the metersand gateway nodes. An exemplary gateway node includes the Silver SpringNetwork Gateway node that uses the AxisPortal V2.2 and common carrierwide area networks such as telephone, code-division multiple access(“CDMA”) cellular networks. Other exemplary gateway node includes theSilver Spring Network AxisGate Network Gateway.

Circuitry of Gateway Node

FIG. 7 shows a block diagram of the gateway node circuitry. The RFtransceiver section 94 of gateway node 72 is the same as the RFtransceiver section 60 of electric meter 10 and certain portionsthereof, such as the spread spectrum processor and frequencysynthesizer, are shown in greater detail in FIG. 7. The gateway node 72includes a WAN interface module 96 which may incorporate electroniccircuitry for a two-way pager, power line carrier (PLC), satellite,cellular telephone, fiber optics, cellular digital packet data (CDPD)system, personal communication services (PCS), or other commerciallyavailable fixed wide area network (WAN) system. The construction of WANinterface module 96 and initialization microcontroller 98 may changedepending on the desired WAN interface. RF channel selection isaccomplished through an RF channel select bus 100 which interfacesdirectly with the initialization microcontroller 98.

Initialization microcontroller 98 controls all node functions includingprogramming spread spectrum processor 102, RF channel selection infrequency synthesizer 104 of RF transceiver 94, transmit/receiveswitching, and detecting failures in WAN interface module 96.

Upon power up, initialization microcontroller 98 will program theinternal registers of spread spectrum processor 102, read the RF channelselection from the electric meter 10, and set the system forcommunication at the frequency corresponding to the channel selected bythe meter 10.

Selection of the RF channel used for transmission and reception isaccomplished via the RF channel select bus 100 to initializationmicrocontroller 98. Valid channel numbers range from 0 to 23. In orderto minimize a possibility of noise on the input to initializationmicrocontroller 98 causing false channel switching, the inputs have beendebounced through software. Channel selection data must be present andstable on the inputs to initialization microcontroller 98 forapproximately 250 μs before the initialization microcontroller willaccept it and initiate a channel change. After the channel change hasbeen initiated, it takes about 600 μs for frequency synthesizer 104 ofRF transceiver 94 to receive the programming data and for theoscillators in the frequency synthesizer to settle to the changedfrequency. Channel selection may only be completed while gateway node 72is in the receive mode. If the RF channel select lines are changedduring the transmit mode the change will not take effect until after thegateway node has been returned to the receive mode.

Once initial parameters are established, initialization microcontroller98 begins its monitoring functions. When gateway node 72 is in thereceive mode, the initialization microcontroller 98 continuouslymonitors RF channel select bus 100 to determine if a channel change isto be implemented.

For receiving data, gateway node 72 monitors the electric meter 10 todetermine the presence of data. Some additional handshaking hardware maybe required to sense the presence of a spread spectrum signal.

An alarm message is sent automatically by electric meter 10 in the eventof a tamper or alarm condition, such as a power outage. The message issent periodically until the error has cleared. Gateway node 72 must knowhow many bytes of data it is expecting to see and count them as theycome in. When the proper number of bytes is received, reception isdeemed complete and the message is processed. Any deviation from theanticipated number of received bytes may be assumed to be an erroneousmessage.

During the transmit mode of gateway node 72, initializationmicrocontroller 98 monitors the data line to detect idle conditions,start bits, and stop bits. This is done to prevent gateway node 24 fromcontinuously transmitting meaningless information in the event a failureof WAN interface module 96 occurs and also to prevent erroneous trailingedge data from being sent which cannot terminate transmissions in atimely fashion. The initialization microcontroller 98 will not enable RFtransmitter 106 of RF transceiver 94 unless the data line is in theinvalid idle state when communication is initiated.

A second watchdog function of initialization microcontroller 98 whengateway node 72 is in the transmit mode is to test for valid start andstop bits in the serial data stream being transmitted. This ensures thatdata is read correctly. The first start bit is defined as the firstfalling edge of serial data after it has entered the idle stage. Allfurther timing during that communication episode is referenced from thatstart bit. Timing for the location of a stop bit is measured from theleading edge of a start bit for that particular byte of data.Initialization microcontroller 98 measures an interval which is 9.5 bittimes from that start bit edge and then looks for a stop bit. Similarly,a timer of 1 bit interval is started from the 9.5 bit point to look forthe next start bit. If the following start bit does not assert itselfwithin 1 bit time of a 9.5 bit time marker a failure is declared. Theresponse to a failure condition is to disable RF transmitter 106.

Communication to and from electric meter 10 may be carried out in one ofa preselected number, for example 24 channels in a preselected frequencyband, for example 902-928 MHz. The meter 10 receives data and transmitsa response on a single RF channel which is the same for both transmitand receive operation. As hereinafter described, the specific RF channelused for communication is chosen during commissioning and installationof the unit and loaded into memory. The RF channel is chosen to bedifferent from the operating channels of other, adjacent interfacemanagement units, thereby to prevent two or more interface managementunits from responding to the same interrogation signal.

Frequency synthesizer 104 performs the modulation and demodulation ofthe spread spectrum data provided by spread spectrum processor 60 onto acarrier signal and demodulation of such data from the carrier signal.The RF transceiver has separate transmitter 106 and receiver 108sections fed from frequency synthesizer 104.

The output of the spread spectrum processor to frequency synthesizercomprises a 2.4576 MHz reference frequency signal in conductor and a PNencoded base band signal in conductor. Frequency synthesizer maycomprise a National Semiconductor LMX2332A Dual Frequency Synthesizer.

The direct sequence modulation technique employed by frequencysynthesizer uses a high rate binary code (PN code) to modulate the baseband signal. The resulting spread signal is used to modulate thetransmitter's RF carrier signal. The spreading code is a fixed length PNsequence of bits, called chips, which is constantly being recycled. Thepseudo-random nature of the sequence achieves the desired signalspreading, and the fixed sequence allows the code to be replicated inthe receiver for recovery of the signal. Therefore, in direct sequence,the base band signal is modulated with the PN code spreading function,and the carrier is modulated to produce the wide band signal.

Minimum shift keying (MSK) modulation is used in order to allow reliablecommunications, efficient use of the radio spectrum, and to keep thecomponent count and power consumption low. The modulation performed byfrequency synthesizer 72 is minimum shift keying (MSK) at a chip rate of819.2 Kchips per second, yielding a transmission with a 6 dBinstantaneous bandwidth of 670.5 KHz.

The receiver bandwidth of this spread spectrum communication techniqueis nominally 1 MHz, with a minimum bandwidth of 900 KHz. Frequencyresolution of the frequency synthesizer is 0.2048 MHz, which will beused to channelize the band into 24 channels spaced a minimum of 1.024MHz apart. This frequency channelization is used to minimizeinterference between interface management units within a commoncommunication range as well as providing growth for future, advancedfeatures associated with the data communication system.

Frequency control of the RF related oscillators in the system isprovided by dual phase locked loop (PLL) circuitry within frequencysynthesizer. The phase locked loops are controlled and programmed byinitialization microcontroller via a serial programming control bus,FIG. 7. The frequency synthesizer produces two RF signals which aremixed together in various combinations to produce a transmission carrierand to demodulate incoming RF signals. The transmission carrier is basedon frequencies in the 782-807 MHz range and the demodulation signal isbased on frequencies in the 792-817 MHz range. These signals may bereferred to as RF transmit and RF receive local oscillation signals.

Table 1 below is a summary of the transmission channel frequencies andassociated frequency synthesizer transmit/receive outputs. The signalsin the table are provided by the two PLL sections in the dual frequencysynthesizer.

TABLE 1 Channel Channel Transmit Local Receive Local Number Frequency(MHz) Oscillation (MHz) Oscillation (MHz) 0 902.7584 782.3360 792.1664 1903.7824 783.3600 793.1904 2 904.8064 784.3840 794.2144 3 905.8304785.4080 795.2384 4 906.8544 786.4320 796.2624 5 907.8784 787.4560797.2864 6 908.9024 788.4800 798.3104 7 910.1312 789.7088 799.5392 8911.1552 790.7328 800.5632 9 912.1792 791.7568 801.5872 10 913.2032792.7808 802.6112 11 914.2272 793.8048 803.6352 12 915.2512 794.8288804.6592 13 916.2752 795.8528 805.6832 14 917.2992 796.8768 806.7072 15918.3232 797.9008 807.7312 16 919.9616 799.5392 809.3696 17 920.9856800.5632 810.3936 18 922.0096 801.5872 811.4176 19 923.2384 802.8160812.6464 20 924.2624 803.8400 813.6704 21 925.2864 804.8640 814.6944 22926.3104 805.8880 815.7184 23 927.3344 806.9120 816.7424

A third signal, which is fixed at 120.4224 MHz, is also supplied by thedual frequency synthesizer. This signal is referred to as theintermediate frequency (IF) local oscillation signal.

In transmission mode, frequency synthesizer 104 provides a signal havinga frequency in the 782-807 MHz range, modulated with the data to betransmitted. RF transmitter section 106 mixes the signal with the fixedfrequency IF local oscillator signal. This results in an RF signal whichranges between 902 MHz and 928 MHz. The signal is filtered to reduceharmonics and out of band signals, amplified and supplied to antennaswitch 110 and antenna 112.

It is recognized that other equivalents, alternatives, and modificationsaside from those expressly stated, are possible and within the scope ofthe appended claims.

1. A method of communicating with utility meters via a network,comprising the following steps: receiving, at a node on the network, arequest to send a message to a meter; in response to the receivedrequest, verifying whether an identifier for said meter is stored atsaid node; and sending the message to said meter if an identifier forsaid meter is verified to be stored at said node.
 2. The method of claim1, wherein said request is received from a utility, and furtherincluding the step of verifying whether the utility is registered withthe node, based upon one or more utility identifiers stored at saidnode.
 3. The method of claim 2, wherein said node is a gateway node thatcommunicates with meters via a first network, and communicates with autility via a second network, and wherein said step of sending themessage includes the step of converting a data stream from a formatassociated with the second network into a data stream associated withthe first network.
 4. The method of claim 3 wherein said first networkis a wireless network, and the message sent to the meter comprises aradio frequency data stream.
 5. The method of claim 1, wherein saidrequest is generated within the node in response to a predeterminedcondition.
 6. The method of claim 5, wherein the node stores a scheduleof times for sending messages to meters, and said predeterminedcondition comprises the occurrence of a scheduled time.
 7. The method ofclaim 6 wherein, in response to the occurrence of a scheduled time, saidnode retrieves the stored identifier of each meter to which a message isto be sent according to said schedule, and sends the message to eachmeter whose stored identifier was retrieved.
 8. A method of obtainingdata from utility meters via a network, comprising the following steps:storing, in a node on the network, a schedule for sending messages tometers and a respective identifier for each of a plurality of meters; inresponse to a condition specified in said schedule, retrieving thestored identifier of each meter that is indicated in said schedule asbeing associated with said condition; and sending a message to eachmeter whose stored identifier was retrieved.
 9. The method of claim 8,further including the steps of receiving data from one or more meters towhich the message was sent, and forwarding said received data to autility connected to the node.
 10. The method of claim 8, wherein saidcondition comprises the occurrence of a scheduled reading time.
 11. Amethod of communicating with utility meters via a network, comprisingthe following steps: receiving, at a node on the network, a message froma meter that contains a unique identifier for the meter; in response tothe received message, verifying whether the meter identifier containedin said message is stored at said node; and processing the receivedmessage at said node if the meter identifier is verified to be stored atsaid node.
 12. The method of claim 11, wherein the step of processingthe message comprises forwarding data in the received message to autility.
 13. The method of claim 12, wherein said node comprises agateway that communicates with the meters via a first network, andcommunicates with a utility via a second network, and wherein said stepof forwarding data in the received message includes the step ofconverting a data stream from a format associated with the first networkinto a data stream associated with the second network.
 14. The method ofclaim 13 wherein said first network is a wireless network, and themessage received from the meter comprises a radio frequency data stream.15. A gateway node in a utility network, comprising: a memory; and aprocessor that is responsive to a request to send a message to a meter,to verify whether an identifier for said meter is stored in said memory,and to send the message to said meter if an identifier for said meter isverified to be stored in said memory.
 16. The gateway node of claim 15,wherein said gateway node communicates with meters via a first network,and communicates with a utility via a second network, and wherein saidprocessor converts a data stream from a format associated with thesecond network into a data stream associated with the first network tosend the message to the meter.
 17. The gateway node of claim 16 whereinsaid first network is a wireless network, and the message sent to themeter comprises a radio frequency data stream.
 18. A gateway in autility network, comprising: memory storing a schedule for sendingmessages to meters and a respective identifier for each of a pluralityof meters; and a processor that is responsive to a condition specifiedin said schedule, to retrieve the stored identifier of meters that areindicated in said schedule as being associated with said condition, andto send a message to each meter whose stored identifier was retrieved.19. The gateway of claim 18, wherein data is received from one or moremeters to which the message was sent, and said processor forwards saidreceived data to a utility connected to said gateway.
 20. The gateway ofclaim 19, wherein said gateway communicates with meters via a firstnetwork, and communicates with the utility via a second network, andwherein said processor converts received data from a format associatedwith the first network into a data stream associated with the secondnetwork to send the message to the meter.